TW201435386A - Zoom lens - Google Patents

Abstract

An embodiment of this invention provides a zoom lens, which comprises a plurality of lens groups in order from an object side to an image-forming side with positive, negative, positive, and positive refractive power respectively. The lens groups comprise a plurality of aspheric lenses and/or free form lenses and a plurality of plastic lenses. The zoom lens satisfies the following equation: DG/fw < 3.5 and TTL/fw < 15.5, wherein DG denotes the total summation of the thickness of each lens group, fw denotes the focal length of the zoom lens at the wide-angle end, and TTL denotes a total thickness of the zoom lens at the wide-angle end.

Description

Zoom lens

The invention relates to a zoom lens, in particular to a light and thin, high magnification A zoom lens with good imaging quality.

Image capture device, including but not limited to digital cameras or digital cameras, usually The image of the object to be captured is captured by the lens module and the image sensor, wherein the lens module refracts and concentrates the light beam from the object to be imaged by zooming and focusing, and then the image sense The detector converts the analog optical signal into a digital electronic signal for subsequent image processing, storage, and transmission.

The lens module of the image capturing device is usually composed of a plurality of lens groups, and Generally, the smaller the total number of lenses of the lens module, the lower the cost and the smaller the overall size. However, a lens module with a low lens count may not be able to meet the requirements of high magnification, and a lens module with a high number of lens groups may not be able to meet the requirements of thinness and thinning.

In view of this, it is urgent to propose a new zoom lens that can simultaneously reduce costs. And to meet the requirements of the zoom lens for thin and light, high magnification, and high image quality.

One of the objects of the embodiments of the present invention is to provide a zoom lens to achieve light Thin, high magnification and high image quality requirements.

According to the above object, an embodiment of the present invention provides a zoom lens, the zoom lens The head includes a four lens group having positive, negative, positive, and positive refracting power from the object side to the image side, respectively. The lens groups comprise a plurality of aspherical lenses and/or freeform lenses, and a plurality of plastic lenses. The zoom lens satisfies the following relationship: DG/fw<3.5 and TTL/fw<15.5, where DG is the sum of the thicknesses of the lens groups, fw is the focal length of the zoom lens at the wide angle end, and TTL is the zoom lens at the telephoto end. The total length of the lens.

Thereby, the invention can provide a light and thin, high condition under the condition of reducing the cost. Zoom lens with high magnification and high image quality.

ZL‧‧‧ zoom lens

F‧‧‧Filter

G1‧‧‧first lens group

I‧‧‧ imaging surface

G2‧‧‧second lens group

C‧‧‧ flat glass

G3‧‧‧ third lens group

L11‧‧‧ first lens

G4‧‧‧Fourth lens group

L12‧‧‧ second lens

OA‧‧‧ optical axis

L21‧‧‧ first lens

DG1‧‧‧first lens group thickness

L22‧‧‧second lens

DG2‧‧‧second lens group thickness

L23‧‧‧ third lens

DG3‧‧‧third lens group thickness

I31‧‧‧ first lens

DG4‧‧‧4th lens group thickness

L32‧‧‧second lens

S‧‧‧Light

L41‧‧‧ first lens

The first figure shows the zoom lens of the preferred embodiment of the present invention at the telephoto end and the wide angle The position of each lens at the end.

2A to 2B respectively show a zoom lens according to an embodiment of the present invention Field curvature characteristics at the wide-angle end and the telephoto end.

3A and 3B show a zoom lens according to an embodiment of the present invention, respectively Distortion characteristics at the wide-angle end and the telephoto end.

4A and 4B respectively show a zoom lens according to an embodiment of the present invention The lateral chromatic aberration curve at the wide-angle end and the telephoto end.

The embodiments of the present invention will be described in detail below with reference to the drawings. except this The present invention may be widely practiced in other embodiments, and any alternatives, modifications, and equivalent variations of the described embodiments are included in the scope of the present invention, and the scope of the following patents shall prevail. . In the description of the specification, numerous specific details are set forth in the description of the invention. In addition, well-known steps or elements are not described in detail to avoid unnecessarily limiting the invention. The same or similar elements in the drawings will be denoted by the same or similar symbols. It is specifically noted that the drawings are for illustrative purposes only and do not represent the actual dimensions or quantities of the components unless otherwise specified.

The first figure shows the zoom lens ZL of the preferred embodiment of the present invention at the wide angle end The position of each lens at (wide) and telephoto (tele). In order to reveal the features of the embodiment, only the structure related to the present embodiment is shown, and the rest of the structure is omitted. The zoom lens ZL of the present embodiment can be applied to a device having an image projection or capture function, such as a digital camera, a digital camera, a mobile phone, or a projector.

As shown in the first figure, in the present embodiment, the zoom lens ZL mainly includes four transparent lenses. The mirror group, from the object side to the image-forming side, is sequentially the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4. The four lens groups along The optical axis OA is set, and the imaging plane I is formed on the image side. Wherein, the first lens group G1 has a positive refracting power, the second lens group G2 has a negative refracting power, the third lens group G3 has a positive refracting power, the fourth lens group G4 has a positive refracting power, and the imaging surface I can be provided with a photoelectric conversion function. Image sensor.

Referring again to the first figure, in an embodiment, the zoom lens ZL satisfies the following conditions: DG/fw<3.5. Wherein, DG is the sum of the thickness DG1 of the first lens group, the thickness DG2 of the second lens group, the thickness DG3 of the third lens group, and the thickness DG4 of the fourth lens group, that is, DG=DG1+DG2+DG3+DG4 And fw is the focal length of the zoom lens ZL at the wide angle end.

In another embodiment, the zoom lens ZL can further satisfy the following conditions: TTL/fw<15.5. Wherein, the TTL is the total length of the lens of the zoom lens ZL at the telephoto end, and the total length of the lens is defined as the distance from a surface of the first lens G1 close to the object side to the imaging surface I; fw is the focal length of the zoom lens ZL at the wide angle end.

In addition, in another embodiment, the zoom lens ZL can also satisfy the following conditions: Ft / fw > 9.5, which means that the zoom lens ZL magnification can reach 9.5 times or more. Where fw is the focal length of the zoom lens ZL at the telephoto end, and fw is the focal length of the zoom lens ZL at the wide angle end.

As shown in the first figure, the zoom lens ZL of the present embodiment reveals four lenses. The group is the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4, respectively, and a total of eight lenses are employed. Among them, the zoom lens ZL can have a solid focal length of less than 28 mm, which is equivalent to 135 mm of a conventional film type camera; and the half image height (Y) at the wide angle end can be greater than 3.3 mm, but not This is limited to this.

In addition, in another embodiment, the aperture S (stop) of the zoom lens ZL of the present invention A fixed aperture can be used, and a variable aperture iris can no longer be used. In the present embodiment, the aperture value (F number, Fno) of the zoom lens ZL at the wide angle end may be less than 3.6, and the aperture value at the telephoto end may be less than 7.0.

In addition, in another embodiment, the total length of the lens of the zoom lens ZL of the present invention It refers to the distance from the surface of the first lens G1 near the object side to the imaging surface I. When the zoom lens ZL is in the retracted position, or when the electronic device equipped with the zoom lens ZL is in the off state, the total length of the lens can be less than 18 mm; when the zoom lens ZL is at the telephoto end, the total length of the lens is defined as TTL. . In practice, the first, second, and third of the zoom lens ZL are in the storage position. At least one of the third and fourth lens groups G1, G2, G3, and G4 may also be moved out of the optical axis OA to make the zoom lens ZL thinner, without limiting the present invention.

As shown in the first figure, in another embodiment, the zoom lens ZL further includes a stop. S and filter F. The aperture S is disposed between the second lens group G2 and the third lens group G3, and can be used to limit the light flux entering the third lens group G3 through the first lens group G1 and the second lens group G2; the filter F is set Between the fourth lens group G4 and the imaging surface I, the invisible light in the incident light beam can be filtered out, wherein the filter F can be an infrared filter. In addition, the imaging surface I can be used to receive the light beam passing through the filter F, and between the imaging surface I and the filter F, the flat glass C can also be added as a cover glass of the image capturing unit.

In this embodiment, when the zoom lens ZL is zooming, each lens group can be along The optical axis OA moves. The movement of the first lens group G1, the second lens group G2, and the third group lens G3 can be used to change the magnification and correct the aberration, and the movement of the fourth lens group G4 can be used for focusing.

Referring again to the first figure, in another embodiment, the zoom lens ZL includes four aspherical lenses and/or freeform lenses. Specifically, the first lens group G1, the second lens group G2, the third group lens G3, and the fourth group lens G4 each include one or two aspherical lenses, one or two free-form lenses, or an aspheric lens. And a free-form lens, which may be made of plastic or glass, wherein the plastic material may include, but is not limited to, polycarbonate, cyclic olefin copolymer (such as APEL), and polyester resin (such as OKP4 or OKP4HT) and so on. In addition, each of the freeform lenses has at least one surface of continuous free curvature, and each aspherical lens has at least one aspherical surface, and each aspherical surface can satisfy the following mathematical formula:

Where Z is the coordinate value in the direction of the optical axis OA, the light transmission direction is the positive direction, A ₄ , A ₆ , A ₈ , A ₁₀ and A _{12 are} aspherical coefficients, K is a quadratic constant, C=1/ R, R is the radius of curvature, Y is the coordinate value orthogonal to the optical axis direction, and the upper direction is the positive direction. In addition, the values of the parameters or coefficients of the aspherical mathematical formula of each aspherical lens can be set separately.

In another embodiment, the first lens group G1 is sequentially included from the object side to the image side. a first lens L11 having a negative refracting power and a second lens L12 having a positive refracting power; the second lens group G2 sequentially includes a first lens L21 having a negative refracting power and a second lens L22 having a negative refracting power from the object side to the image side. The third lens L23 having positive refractive power; the third lens group G3 includes a first lens L31 having positive refractive power and a second lens L32 having negative refractive power; and the fourth lens group G4 includes a first lens L41 having positive refractive power. In this embodiment, the first lens L11 may be a convex-concave lens with a negative refractive power convex toward the object side, the second lens L12 may be a positive refractive power lenticular lens, and the first lens L21 may be a negative refractive power of the convex surface toward the object side. The convex-concave lens, the second lens L22 may be a convex-concave lens having a negative refractive power toward the object side, the third lens L23 may be a convex-concave lens having a positive refractive power on the convex side, and the first lens L31 may be a lenticular lens having a positive refractive power. The second lens L32 may be a convex-concave lens having a convex refracting convex side toward the object side, and the first lens L41 may be a positive refracting lenticular lens, but is not intended to limit the present invention.

In another embodiment, the third lens L23 of the second lens group G2, the third through The first lens L31 and the second lens L32 of the mirror group G3, and the first lens L41 of the fourth lens group G4 may employ an aspherical lens or a free-form lens; and the first lens L11 and the second lens of the first lens group G1 L12, and the first lens L21 and the second lens L22 of the second lens group G2 may employ a spherical lens. The free-form lens has at least one free curvature surface, the aspheric lens has at least one aspherical surface, and the spherical lens may be spherical on both sides, but not limited thereto.

In another embodiment, the first lens L11, the second lens L12, and the first lens The L21, the second lens L22, and the first lens L31 may be made of a glass lens made of a nitrate material; and the third lens L23, the second lens L32, and the first lens L41 may be plastic lenses made of plastic. Specifically, the glass lens may be made of an optical grade of a nitrate material, and in the embodiment, the first lens L31 may also be an aspheric surface made by grinding or glass molding process (GMP). Lens or free-form lens; plastic lenses can be made by injection molding or turning, but not limited to this.

In addition, in still another embodiment, the refractive index of the third lens L23 is greater than 1.6 and The Abbe number is less than 50; the refractive index of the first lens L31 is less than 1.6 and the Abbe number is greater than 50; the refractive index of the second lens L32 is greater than 1.6 and the Abbe number is less than 50; the refraction of the first lens L41 The rate is less than 1.6 and the Abbe number is greater than 50. However, it is not intended to limit the invention.

Table 1 lists the details of an example of the zoom lens ZL according to the first embodiment of the present invention. The data includes the radius of curvature, thickness, refractive index, dispersion coefficient, and the like of each lens. The surface code of the lens is sequentially arranged from the object side to the image side. For example, "S1" represents the surface of the first lens L11 toward the object side, "S2" represents the surface of the first lens L11 toward the image side, and "STOP" represents The surface of the aperture S, "S18" and "S19" respectively represent the surface of the filter F toward the object side and the image side, and "S20" and "S21" respectively represent the surface of the sheet glass C toward the object side and the image side. Wait.

In Table 1, "thickness" represents the distance between the surface and a surface adjacent to the image side. For example, the "thickness" of the surface S1 is the distance between the surface S1 and the surface S2, and the "thickness" of the surface S2 is the distance between the surface S2 and the surface S3. If the thickness values are indicated as "D1", "D2", "D3" and "D4", the distance between the two surfaces is different according to the wide angle and the telephoto end. The distance is shown in Table 2. At the same time, Table 2 also lists the focal length of the zoom lens ZL at the wide-angle end and the telephoto end.

In addition, the third lens L23, the first lens L31, and the second through lens in the above example The two surfaces of the mirror L32 and the first lens L41, that is, the surface numbers are "S9", "S10", "S12", "S13", "S14", "S15", "S16" and "S17", in the aspherical mathematical formula The various coefficients are shown in Table 3.

In an example, the focal length fw of the zoom lens ZL at the wide angle end may be Between 4.25 mm and 5.00 mm, the DG value can be less than 14.85 mm, so the value of DG/fw is about 2.97~3.494<3.5. In the present example, the focal length fw of the zoom lens ZL at the wide-angle end is 4.558 mm, the DG value is 14.25 mm, and DG/fw = 3.16.

In an example, the focal length ft of the zoom lens ZL at the telephoto end can be Between 40.37 mm and 62.5 mm, the magnification of the zoom lens ZL is ft/fw=9.5~12.5≧9.5. In the present example, the focal length ft of the zoom lens ZL at the telephoto end is 52.546 mm, so the magnification ft/fw of the zoom lens ZL is 11.528.

In an example, the total length of the lens of the zoom lens ZL at the telephoto end may be Between 55.0 mm and 65.5 mm, the value of TTL/fw is approximately 11.0~15.41<15.5. In this example, the total lens TTL of the zoom lens ZL at the telephoto end is 60.07 mm, so the value of TTL/fw is 13.179.

In addition, in an example, the aperture value of the zoom lens ZL at the wide angle end (F Number, Fno) may be less than 3.6, and the aperture value at the telephoto end may be less than 7.0. In the present example, the zoom lens ZL has an aperture value (F number, Fno) of 3.2 at the wide-angle end and an aperture value of 6.5 at the telephoto end.

2A to 2B respectively show a zoom lens according to an embodiment of the present invention ZL field curvature curve at the wide angle end and the telephoto end. Among them, the curves T and S respectively show the aberrations of the zoom lens ZL for the Tangential Rays and the Sagittal Rays. In the present embodiment, at the wide-angle end, the tangential field curvature and the sagittal field curvature of the beams of various wavelengths are controlled within the range of (-0.05 mm, 0.07 mm); at the telephoto end, the tangential field curvature and the arc The field curvature values are controlled in the range of (-0.15 mm, 0.18 mm).

3A and 3B show a zoom lens according to an embodiment of the present invention, respectively Distortion curve of ZL at the wide-angle end and the telephoto end. In the present embodiment, at the wide-angle end, the distortion rate of the beams of various wavelengths is controlled within the range of (-16%, 0%); at the telephoto end, the distortion rate is controlled within the range of (0%, 2.5%).

4A and 4B respectively show a zoom lens according to an embodiment of the present invention The lateral color of the ZL at the wide-angle end and the telephoto end. In the present embodiment, the lateral chromatic aberration of the beams of various wavelengths is controlled within the range of (-0.5 μm, 3.5 μm) at the wide-angle end, and the lateral chromatic aberration is controlled within the range of (-3 μm, 0.5 μm) at the telephoto end.

It can be seen from the second to fourth B drawings that the zoom lens ZL of the embodiment of the present invention Good correction can be obtained for field curvature, distortion and lateral chromatic aberration at the wide-angle end and the telephoto end. Moreover, the zoom lens ZL of the embodiment of the present invention has the characteristics of low cost, small size, high magnification, and good image quality.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; all other equivalent changes or modifications which are not departing from the spirit of the present invention should be included in the following. Within the scope of the patent application.

ZL‧‧‧ zoom lens

F‧‧‧Filter

G1‧‧‧first lens group

I‧‧‧ imaging surface

G2‧‧‧second lens group

C‧‧‧ flat glass

G3‧‧‧ third lens group

L11‧‧‧ first lens

G4‧‧‧Fourth lens group

L12‧‧‧ second lens

OA‧‧‧ optical axis

L21‧‧‧ first lens

DG1‧‧‧first lens group thickness

L22‧‧‧second lens

DG2‧‧‧second lens group thickness

L23‧‧‧ third lens

DG3‧‧‧third lens group thickness

L31‧‧‧ first lens

DG4‧‧‧4th lens group thickness

L32‧‧‧second lens

S‧‧‧Light

L41‧‧‧ first lens

Claims (12)

A zoom lens, comprising: a first lens group, a second lens group, a third lens group, and a fourth lens group, wherein the second lens group has a negative refracting power, and the first lens group The two lens groups, the third lens group and the fourth lens group each comprise at least one plastic lens. The zoom lens of claim 1, wherein the zoom lens satisfies the following relationship: DG/fw<3.5, wherein DG is the first lens group, the second lens group, the third lens group, and the first The sum of the thicknesses of the four lens groups, fw is the focal length of the zoom lens at the wide angle end. The zoom lens of claim 1, wherein the zoom lens satisfies the following condition: TTL/fw<15.5, wherein TTL is the total length of the lens of the zoom lens at the telephoto end, and fw is the focal length of the zoom lens at the wide angle end. The zoom lens of claim 1, wherein the zoom lens satisfies the following condition: ft/fw>9.5, wherein ft is a focal length of the zoom lens at a telephoto end, and fw is a focal length of the zoom lens at a wide angle end. The zoom lens of claim 1, wherein the zoom lens has an aperture value of less than 3.6 at the wide-angle end and an aperture value of less than 7.0 at the telephoto end. The zoom lens according to any one of claims 1 to 5, wherein the second lens group, the third lens group, and the fourth lens group each include at least one of an aspherical lens and a free-form lens. The zoom lens of claim 6, wherein the second lens group comprises three lenses, having negative, negative and positive refracting power from the object side to the image side, respectively, and the refractive index of the third lens closest to the image side is greater than 1.6, Abbe number is less than 50. The zoom lens of claim 6, wherein the third lens group includes a first lens having positive refracting power and a second lens having negative refracting power from the object side to the image side, the first lens having a refractive index smaller than 1.6. The Abbe number is greater than 50, the refractive index of the second lens is greater than 1.6, and the Abbe number is less than 50. The zoom lens of claim 6, wherein the fourth lens group comprises an aspheric plastic lens or a free-form plastic lens having a refractive index of less than 1.6 and an Abbe number greater than 50. A zoom lens comprising, from the object side to the image side, at least: a first lens group having a positive refracting power, a second lens group having a negative refracting power, and a third lens group having a positive refracting power, wherein the second lens group And the third lens group each includes at least one of an aspheric lens and a free-form lens, and the second lens group and the third lens group each include a plastic lens. The zoom lens of claim 10, further comprising a fourth lens group disposed between the third lens group and the image side and including an aspherical plastic lens and/or a free curved surface Plastic lens. A zoom lens comprising: four lens groups each having positive, negative, positive and positive refracting powers, wherein the lens groups comprise a plurality of aspherical lenses and/or free-form surface lenses, and a plurality of lens lenses Plastic lens.